Cell Biology: Mitochondria Energy

8/12/2019 Cell Biology: Mitochondria Energy

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Bacteria, mitochondria and chloroplastsall use chemiosmosis to generate ATP


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Mitochondria contain two membranes and two aqueous compartmentseach of which contains a unique set of proteins.

Fig 5.3 p181


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Fig 3.27 p113


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Fig 5.5 p183


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The mitochondrial inner membrane and matrix are the sites of

most reactions involving the oxidation of pyruvate and the coupled synthesis of ATP


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Mitochondrial oxidation of pyruvate beginswith the formation of acetyl CoA


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The multienzyme complex pyruvate dehydrogenase convertspyruvate and coenzyme A into CO 2 and acetyl CoA


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From glycolysis,Pyruvate decarboxylase

From oxidation of fatty acidsIn mitochondria

Aka TCA, Krebs cycle


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Fig 5.6 p185

Tricarboxylic Acid (TCA)CycleKrebs Cycle Citric acid cycle


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A summary of the reactions ofglycolysis and the citric acid cycle


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Electron transport and oxidativephosphorylation

Most of the free energy released during oxidation of glucoseto CO 2 is retained in NADH and FADH 2 During respiration, electrons are released from NADH andFADH 2 and eventually are transferred to O 2 (forming H 2O)The step-by-step transfer of electrons via the electrontransport chain allows the large amount of free energyproduced by the transfer of electrons to O 2 to be released insmall increments

Several electron transport chain components convert thesesmall increments into a proton and voltage gradient acrossthe inner membraneThe movement of protons down their electrochemical

gradient drives the synthesis of ATP from ADP and P i


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The stepwise flow of electrons through the electrontransport chain from NADH, succinate, and FADH 2 to 0 2

Reduction

potentials ofelectron carriersfavor electronflow from NADHto O 2


15/46Fi 5.14 192


16/46Table 5.1 p190


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Electron transport in mitochondria iscoupled to proton translocation


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The multiprotein complexes and associated prostheticgroups of the mitochondrial electron transport chain


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The pathway of electron transport and protontransport in the inner mitochondrial membrane

Fig 5.17 p194


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NADH FAD

1

2

_ O 2 H O2

FMN

Fe-S

Fe-S

Fe-S

Q

Matrix

Inner Memb

ComplexI Complex

II

ComplexIII

ComplexIV


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NADH FAD

1

2

_ O 2 H O2

FMN

Fe-S

Fe-S

Fe-S

Q

Matrix

Inner Memb

ComplexI Complex

II

ComplexIII

ComplexIV

H+

H+

H+


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Fig 5.10 p187


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Coenzyme Q is the only electron carrier thatis not a protein-bound prosthetic group

Th di i l f i


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Three-dimensional structures of some iron-sulfur clusters in electron-transporting proteins

Fig 5.13 p192

O id i f d d h b h


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Oxidation of reduced cytochrome c by cytochrome coxidase is coupled to proton transport

C li f H + i d O d i


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Coupling of H + pumping and O 2 reductionby cytochrome c oxidase

Fig 5.18 p195


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Uncoupler

2,4-dinitrophenol (DNP)

Thermogenin

Natural uncouplerBrown adipose tissue

h


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ATP Synthase

Fig 5.22 p199


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Fig 5.3 p181

ATP th i t h l


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ATP synthase comprises a proton channel(F 0) and ATPase (F 1)

Fig 5.24 p200


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Fig 5.24 p200

Fi 5.29 204

Proton Diffusion


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ATP Synthase F1 Head

Fig 5.26 p202

The F F comple harnesses the proton


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The F 0F1 complex harnesses the proton-motive force to power ATP synthesis

Binding Change Mechanism

Fig 5.27 p203


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Demonstration that the subunit of F 0 rotates relative to the( )3 hexamer in an energy-requiring step

Fig 5.28 p203


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Fig 5.30 p205

Summary


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Specific uptake-targeting sequences in newly madeproteins are recognized by different organelles

Overview of sorting of nuclear


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Overview of sorting of nuclear-encoded proteins in eukaryotic cells


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Most mitochondrial proteins are synthesized asprecursors containing uptake-targeting sequences

Uptake targeting sequences of imported


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Uptake-targeting sequences of importedmitochondrial proteins

Fig 8.47 p317


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Fig 8.47 p317


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Mitochondria and chloroplasts Contain their own

prokaryote-like genomes andribosomes

Likely evolved from

bacteria that wereendocytosed(ingested)

EndosymbiontHypothesis

Fig 1 p27


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Fig 1 p27

Mit h d i d B t i


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Similarities to Bacteriaa) DNA is circularb) Size of ribosome 70sc) antibiotic sensitivity (inhibit protein synthesis)

Chloramphenicol inhibits Mito + Bacteria but notcytosolic ribosmes

Cycloheximide inhibits cytosolic ribosmes but not

Mito + Bacterail ribosomesd) Replication

Mitochondria and Bacteria

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Cell Biology: Mitochondria Energy